The purpose of the Ischemic Heart SCOR proposal at the University of Texas Health Science Center at Dallas is to allow continued effort directed at providing a better understanding and more precise definition of pathophysiological mechanisms operative during myocardial ischemia and evolving myocardial infarction. Research work in this SCOR is built upon the principle that from an improved understanding of fundamental processes operative during myocardial will come improved patient care and rehabilitation and perhaps an ability to prevent myocardial ischemia or infarction in some individuals at risk. Specifically, this Ischemic SCOR Program will continue to devote effort toward: a) developing more precise and sensitive methods for detecting myocardial ischemia and the cellular damage that it causes, and b) developing mechanistic and prognostic insight so as to be able to predict patients at risk for future ischemic events and ultimately intervene in a manner that prevents myocardial ischemia and its consequences. The basic and clinical experimental studies that are conducted will in most instances be continuations of research efforts that have been ongoing during the previous 8 1/2 years. These studies have been productive and have contributed: a) new information related to mechanisms of ischemic heart damage, and b) new technology allowing the detection and estimation of the extent of ischemic heart damage and prognostic insight allowing the identification of the patient at risk for new ischemic heart damage. However, four new research sections, including one to evaluate membrane phospholipid alterations during experimental myocardial ischemia; one to evaluate membrane phospholipid alterations during experimental myocardial ischemia; one to evaluate basic cellular alterations with experimental myocardial ischemia as they are detected by nuclear magnetic resonance imaging; one to evaluate cellular and vascular alterations in prostaglandin synthesis with experimental myocardial ischemia and its component parts; and one to evaluate potential basic cellular differences that may influence ischemic injury and the role of alterations in cytoplasmic calcium concentration in influencing the development of arrhythmias under varing experimental circumstances have been included in this renewal proposal. Ischemic Heart Disease remains a major health hazard in contemporary western society. This Ischemic SCOR Program has been productive and has made important contributions: a) toward the understanding of basic pathophysiological mechanisms involved in the evolution of cellular damage during myocardial ischemia and infarction; b) in the development of sensitive and specific methods for the identification of acute myocardial ischemia and infarction, its localization and estimates of its size; and c) the development of prognostic insight into patients at risk for future ischemic heart disease complications.